What this video covers
The clip covers houseplants as an overlooked indoor moisture source.
Overwatering leaves the top of the soil permanently damp, and white fuzzy growth on the surface is the visible result. In a room with several plants and limited ventilation it also lifts the local humidity.
The takeaway
Let soil dry between waterings and check the surface when you do. It is a small thing, but a row of overwatered pots is a moisture source sitting in the room with you.
Read the full written guide: How to Recognize a Mold Problem.